* Three retired generals given life terms
* Military is guardian of secular establishment
* Court acquits 34 officers
A Turkish court sentenced more than 300 military officers to jail on Friday for plotting to overthrow Prime Minister Tayyip Erdogan almost a decade ago, ending a trial that underscored civilian dominance over the once all-powerful military.
The court in Silivri, just west of Istanbul, handed prison terms to 322 serving and retired army officers and acquitted 34, according to court documents seen by Reuters.
Two retired generals and a retired admiral considered the ringleaders of the so-called "Sledgehammer" plot to topple Erdogan in 2003 were given life terms. Their relatives collapsed in tears in the courtroom as the sentences were handed down.
The military has long been the guardian of Turkey's secular establishment, launching three coups between 1960 and 1980 and pressuring an Islamist-led government to quit in 1997.
But Erdogan's Islamist-rooted AK Party, which came to power a decade ago, has tamed military influence over policy-making and ministerial appointments as part of efforts to strengthen democracy, while prosecutors have pursued suspected coup-makers through the courts.
"To comment without seeing the reasons for the verdict would be inappropriate. There is an appeals process. What is important for us is that the right decision emerges," Erdogan told reporters in Ankara, as the sentences were being announced.
The ruling has the potential to undermine morale in the military as it battles Kurdish militants in the southeast and faces a growing challenge maintaining security along its southern border with war-torn Syria.
"Turkish soldiers are not just being struck down in Diyarbakir, Sirnak and Bingol, it is actually here where they have been hit," said Colonel Mustafa Onsel, one of the defendants, referring to three southeastern provinces which have seen clashes with Kurdish militants in recent months.
The court said the three sentenced to life would in fact only serve 20 years because they were unsuccessful in their bid to topple the government.
The "Sledgehammer" conspiracy is alleged to have included plans to bomb historic mosques in Istanbul and trigger conflict with Greece to pave the way for an army takeover.
Prosecutors had demanded 15 to 20-year jail sentences for the 365 defendants, 364 of whom were serving or retired officers.
Those sentenced to life included retired generals Cetin Dogan and Halil Ibrahim Firtina, and retired admiral Ozden Ornek, considered the ringleaders of the plot.
Those sentenced to 18-year terms included Engin Alan, a retired general elected to parliament as a member of the National Movement Party last year, and Bilgin Baranli, who had been in line to become Air Force commander before his arrest last year.
"MOTIVATED BY REVENGE"
Sledgehammer is one of a series of trials that has sparked criticism that the government is using the courts to silence political opponents.
Others include the "Ergenekon" case, which involves a web of alleged plots against Turkey's government.
Thousands of people, including journalists, lawyers and politicians, are in jail pending verdicts in trials that human rights groups say raise questions about Turkey's commitment to democratic rights.
Dogan's daughter Pinar Dogan, a lecturer at Harvard University, said her family believed the case was aimed at settling old scores and pointed to reports by experts who said computer documents submitted as evidence appeared doctored.
"Going after those perceived as opposed to this government because of its Islamist leaning is motivated in part by revenge. My father was a retired man with no political clout left," she said.
"He had no sympathy for this government, but he would never have bombed mosques or shot down planes, never."
The Turkish military is NATO's second-biggest standing force after the United States. Its main domestic challenge has been militants from the Kurdistan Workers' Party (PKK), considered a terrorist group by Ankara, the United States and European Union.
The past few months have seen some of the heaviest fighting since the PKK took up arms in 1984 with the aim of carving out a Kurdish state. Turkish troops are also serving in Afghanistan, Northern Cyprus and Lebanon as well as at small observation posts set up in the 1990s in Iraq.